The events leading to the onset of various ocular complications are being studied in addition to methods for their potential pharmacological control. Specifically, the relationships between the enzymes aldose reductase and aldehyde reductase and the progression of retinopathy, cataract, pupil function and iris changes, and keratopathy induced by diabetes or galactosemia are being investigated. Methods for either delaying or preventing the onset of these complications through the pharmacological control of these enzymes are also being developed. The biochemical progression of several types of cataracts are also being studied as well as methods for controlling their onset through pharmacological intervention.